So, I loved Buffy and Angel, but I never got around to seeing Firefly. I’ve been talked into seeing Serenity tonight. Is that a terribe plan? Will I understand a thing, or is it fairly stand-alone?
Can someone give me a CLiff’s Notes version of the show? (I know sci-fi geeks hate talking about their favorite show, but bear with me.)
You’ll love it. Go in unspoiled. The movie is self-evident…Joss assumes you have a brain and know how to use it. You’ll get all the info you need in the first 15 minutes. You get layers if you’ve seen Firefly, but it isn’t necessary by any means.
500 years in the future. We’ve used up Earth, so we terraformed a multiplanet system for settlement. The Alliance rules the system. There was a war because some of the outer, poorer planets didn’t want to be part of the Alliance. Mal Reynolds, captain of the Serenity was on the losing side. Now, he and his crew just try to keep flying.
I’ve seen the movie already, and I think you should be able to understand it okay. The only thing that isn’t abundantly clear from the very start is (spoiler for the series, not the movie):
Inara used to live on Serenity, but left because she and the captain obviously had feeeelings for each other which exhibited itself in lots of fighting and sexual tension.
Oh shit, my spoiler actually does contain a very slight spoiler for the movie…something that was implied was going to happen in the series but was never shown, until the comic books. Gah.
Solid. You’ve nailed exactly why I love watching Whedon work: because he knows I can think for myself. As long as he continues doing that, I’m with him.
I’m getting slightly tingly now. 14 hours to go.
By all means, go. My husband and I are fans of the show, but we saw an early screening a few weeks ago with an uninitiated friend. Our friend LOVED it, and immediately borrowed out DVDs of the show, which he watched in about two days time. 
So go, and figure out where you’re going to get the DVDs you will subsequently feel compelled to watch!
Go see it. I agree with Kyla that this is the one thing where the Firefly viewer has a real advantage over others, but it’s a minor point in the film. Anything else, the film tells you everything you need to know. So go see it. Then go buy the Firefly DVD’s, watch 'em, and go see Serenity again. 
–Cliffy